Aircraft landing wheel assembly



y 8, 1952 c. F. ZIMMERMAN ET AL AIRCRAFT LANDING WHEEL ASSEMBLY Filed Aug. 17, 1948 INVENTORS.

CHARLES F. ZIMMERMAN ROBERT E KIBELE F5 Elm/41. w

ATTORNEY.

Patented July 8, i952 (i-2302,61? 7, j AIRCRAFT LANDING WHEEL ASSEMBLY] Application August 17, 1948, swarms-44,714

" "2 claims. (01. 244-163) The present invention relates to aircraft .hav-

ing-castering or steerable duallanding wheels. In certain aircraft having castering udual wheels, particularly'aircraft having tricycle type -landing gearfwith a castering dual wheel assem-' blyforward of the aircraft center ofgravity, it

1 hasi-beenfound that when such dual wheels :are -keyedi together for rotation :asia unit "steering during" ground operation'is :difficult by reason of I the 'tendency of the dual wheelsto track insa; "straight line.

On theother hand it has been observed that when the dual wheels are mounted for free relative rotationthere-is at times a tendency for them to shimmy or to oscillate about the caster axis with the result that it is diflicult to control the aircraft, particularly when the condition arises at high speeds. 3 H

Thepresent inventionprovides a simple; and lightweight means for damping such oscillations of the dual wheels about'the caster axis while at the same time enabling them to rotate relatively so that excessive steering loads are avoided. According to the inventionpne of -the dual wheels may be keyed to an axlexthat is mounted on the airplane for free rotation and also forsteering or casteringmovement, but the other one of the dual wheels is mounted for frictionally resisted rotation upon the axle. The resistance of 'the friction means is such as to constrain the wheels *agairfst relative rotation-sufficiently to' aa ipescillationjsf'of the wheel and axle assemblyi about the caster axis, thereby improving the stability of the airplane during ;.take-offa nd landing runs. At the same time the resistance of the friction .meansis sufiiciently light that the wheels can ro- 'ta'tefirel atively to enable steering the airplane with'no'rmal' control pressures during taxiing operations.

The foregoing and other objects and advantages of the invention will become apparent from the following description of the typical embodiment shown in the accompanying drawings, wherein:

Figure 1 is a side elevation of an airplane of one type to which the invention may be advantageously applied;

Figure 2 is a front elevation of the castering dual nose wheel assembly of the airplane; and,

Figure 3 is a sectional view taken through the hub of the wheel assembly.

As shown in Figure l the airplane, comprising fuselage l0, wing II and engine nacelle l2, has a tricycle type landing gear including a pair of dual landing wheels l3 aft of the airplane center of gravity and a dual nose wheel forward of the center of gravity. The wheels and thesup'porting struts therefor are shown only in their projected o'r'landing positions but it will be understood that they may beretracted into the airplane by suitablemecha'nis'm, not shown." Independently operated brakes, also not shown, are provided on the wheels [3 to enable theusual braking action and steering'o'f the airplane upon the-ground. n r I "The dual nose-wheel assembly comprisesleft and right wheels l4 and I5 mounted on a tubular axle 16 on opposite sides of an axle mounting H.

erably intersects the ground level somewhat forward of .the center of contact with the ground of wheels l4 and I5 so that the nose wheels will caster properly. I

The axle' l6 is supported in mounting 1-1 on tapered roller bearings 22 that are arranged to bear both radial and thrust'loads. Both wheels are mountedf'on the axle by meansof sleeve type bearings 31 pressed into the wheel hubs.

v The left wheel ll is keyed to the axle by a retainer 23 whichis connected'to the wheel by fasteners 24 and has'key projections 25 which seat in complementarykeyways formed in the end of the axle. The-retainer 23 is secured against axial displacement by headed fastener 20 which is screw threaded into the end of the axle.

The right wheel I5 is retained on the axle by'a generally similar arrangement including "a retamer 26 having key projections 21 seating in keyways formed in the end of the axle and a headed fastener 28 for the retainer screw threaded into the axle. Retainer 26, although holding the wheel [4 against axial displacement does not prevent the wheel from rotating upon the axle. The wheel has secured thereto, by fasteners 29 in the illustrated embodiment, an annular friction element 3| which extends radially beyond the periphery of the hub of the wheel to provide an inner annular face that is engageable with the outer face of a, ring 32. The latter is affixed to the retainer 26 by fasteners shown at 33.

The retainer 26 has on its inner face an annular recess 34 which receives the outer portion of friction element 3| and which also contains an annular friction shoe 35 and a crimped spring larly at relatively high speeds as during the landing and takeoff runs,ifrom various factors,

such for example as a, slight dynamic unbalance second retaining member secured in keyed relation to the opposite end of said axle, a ring secured to said second retaining member and having frictional engagement with the inner face of said friction, element, said second retaining member having an annular recessadjacent the outer face of said friction element, an annular i friction shoe disposed 'saichrecess'ffor frictional engagement/with saidfriction element, and resilient means in said recess for urging said shoe into such frictional engagement and simultaneof the wheel and axle assembly. If not dam-pened' such oscillations may increase in magnitudesufiiciently to endanger the aircraft structure and "to cause loss of control of the aircraft i at :high speeds, However the frictional constraint should be :much less than that .requiredto cause the wheels to slide during turns l-in'normal taxiing operations,' and preferably is so light asto not i. increase appreciably'the brakingefforpapplied to wheels l'3for steering theaircraft; j

. The arrangementdescri b-ed-hereinwis :an ex- ,pedient means for .providingthe desired-frictional constraint ibetweenwheels HI and 15, for

it will be noted that the axle itself may 'bes-ymmetrical and thewheelscidentical; ithe friction, :element 3! .;may he bolted to "Wheel 11:5 *in'wthe same relation that retaineriii fis bolted to wheel :14. Flurthermorefthe several "parts of the friction device may :be removed (and replaced without removing either :of :the dual wheels. :How ever it will be understood that various changes =;may bemadeiin the structurea'nd arrangement of .the parts, ;andralso that the invention may be applied to various :typesof castering and steerable wheels. other than nose Wheels, for-=ex-;, H ample .to tail wheels, without departing from the spirit of the invention-or from the scope of the appended claims.

We claim as our invention: 1 a

1. In ,a 'castering dual landing -wheel assent ,bly for aircraft an-axle mounting :having means for rotatably SBCUIiDggitf'tO the aircraftwith its axis :of rotation disposed substantially vertically, said axis of rotationgconstituting the axis of caster of said assembly, an raxlejournaled for 1'0- .tation in said. mounting,:and dual landing wheels 'mounted on saidaxle on opposite sides of said mounting, the combination itherewith of a first retaining membersecured in .keyed relation to- .one end of said axle and securedin abutting relation to the "outer face of one wheel .for fix- .ing thelatter to the axle, a friction element se- ..cur ed to the .outer face of the other wheel, a

1 Number .ou sly urging said ring into said frictional ene sement with the inner face of'said flange,

"whereby said wheels are frictionally constrained against relaftive rotation to damp oscillations of t he"wheel-and:axle and wheel mounting about said;caster; :axis, the wheels being relatively ro tatable against said frictional constraint while the airplane is being turned during ground operation.

EIn iaiscasterin'g-idual landing wheel :assembly for aircraft; an -axle mounting -having:means for rotatablyvsupporting it on :said zairc'raftx-with its axis of rotation1ariangeldfsubstantially vertically,

said axis ofrotation. constitutin .tlIe -axis'of caster 6f :said assemblyfje-ansaxle ijournall'ed :for "ro- 'tati-ninsaid m'ountingfa pair o'fuwheels. mount- I e'd-onsai'd :axle; one' -Ton each side :o'f :me' mount- 1 ingpsa retainer 'plat'e rigidly securedztogeach'outer end of said'raxle'; 'only sone of said iplates being also rigidly s'ecur'edirto one iof satid wheels; :a-first friction element .rigidly'- secured 'to the :other wheel; a second friction aelement ,rigidlylzsecured to the other retainer plate in opposing relationship .to said first ifriction element; and means resiliently urging saidx friction 1 elenientsintogfrictional engagement to thereby provide :a predetermineddegree of frictional resistance r to lro tanonfof said otheriwheehrelative ;tov said 'axlelr' 40- I CHARLESFLYZIIWNEERMAN. I TROBER'I'IE:

' REFERENCE-S- CITED "following references are of record "in "the file of-this patent l 1 eman ti "egrrENTs I Date 

